A multiplexed analysis method based on encoded particles is being highlighted in the field of high efficiency bio-molecular detection such as new drug development and clinical diagnosis, owing to its extendability and fast reaction. The multiplexed analysis method may be realized by mixing a lot of encoded probe particles in a vial containing the target analysis object.
It is necessary to use many distinguishable codes in order to obtain high analyzing efficiency for various samples. In order to ensure a sufficient number of codes, a spectral coding method using quantum dots or phosphors and a graphical coding method based on patterning of optically measurable elements on surfaces of microparticles have been suggested.
However, according to the spectral coding method, there are problems regarding handling of various materials for realizing codes, such as overlapping of spectrums, limited number of materials, expensive costs, and limitation in precise controlling of loading of an indicator material of a small amount. In addition, in the case of the graphical coding method such as a binary barcode, there is a limitation in resolution, and accordingly, a wider area is necessary in order to realize a sufficient number of codes, and the number of codes is limited by the sizes of particles. Therefore, a multi-level coding method using binary or greater codes has been suggested; however, the above method has very complicated processes and it is necessary to precisely load a plurality of indicator materials like in the spectral coding method.
Also, a method of appropriately handling microparticles is necessary in order to read codes in the multiplexed analysis method based on encoded particles. For example, it is not easy to selectively isolate the microparticles from a mixture solution.